In recent years there has been an increased demand to improve, rotary magnetic head apparatus used in, e.g., VTRs. Such improvements included miniaturization, reduction of weight, providing a multiplication of magnetic heads, broadening of frequency band, etc. Also the rotary magnetic head apparatus has been demanded to house, e.g., an amplifier circuit therein.
FIG. 1 is a longitudinal section of a conventional rotary magnetic head apparatus, and FIG. 2 is an exploded prespective view of the conventional rotary magnetic head apparatus. In FIGS. 1 and 2, 21 denotes a rotary drum. To this rotary drum 21 a magnetic head 22 is fastened with screws 23. A rotor 24a of a rotary transformer 24 is fixed to a flange 26 with, e.g., a bonding agent, into which a rotary shaft 25 is inserted. This flange 26 is fastened to the rotary drum 21 with screws. A junction board 27, which is made of epoxy resin, is mounted on the rotor 24a. A winding 28 of the rotor 24a is connected by soldering to the junction board 27. Further, a plurality of first connecting terminals 29 insulated by, e.g., a resin mold are mounted by soldering to the junction board 27 so as to penetrate the rotary drum 21. The winding 28 and the first connecting terminals 29 are electrically connected to each other through the junction board 27. A circuit board 30 provided with electric circuits such as recording and reproducing signal amplifier circuits, mounted on the rotary drum 21, is connected by soldering to the first connecting terminals 29. The magnetic heads 22 and the circuit board 30 are connected by soldering to the second connecting terminals 31, which are insulated with a resin mold and penetrates the rotary drum 21. Further, the rotary shaft 25 of the rotary drum 21 is inserted into a rotary bearing 33 fitted in an inserting hole of the stationary drum 32, to which a stator 24 b of the rotary transformer 24 is bonded. The rotary magnetic head apparatus is thus constructed as described above.
However, in the construction as described above, by increasing the number of connections, the electric characteristic degrades. Further the manufacturing process is complicated because dedicated connecting terminals 29 and 31 were needed for connecting the rotor 24a, the magnetic heads 22 and the circuit board 30.
Also as a construction of an electronic circuit on the rotor 24a requires making the rotor 24a large, the magnetic heads 22 will be concealed by the rotor 24a. Therefore, the magnetic heads 22 could not be connected to the circuit board 30. Further, the circuit board 30 positioned outside the rotary drum 21 was unfavorable for achieving the broadening of the frequency band of recording signals.
In a conventional rotary magnetic head apparatus, dedicated connecting terminals were needed for connecting the rotor, the magnetic heads and the rotary board. Furthermore, increasing the number of connecting points, electric characteristic decreases, and the manufacturing process was complicated.
FIG. 3 shows a conventional connecting device for connecting circuit boards when assembling the rotary magnetic head apparatus. FIG. 3(a) shows a male connector unit. This male connector unit is comprised of a resin mold body 131, male connectors 132, and lead terminals 133. This male connector unit is connected by soldering using the lead terminals 133. This male connector unit is connected by soldering using the lead terminals 133 to connecting pads 135 formed on a circuit board 134.
FIG. 3(b) shows a female connector unit. This female connector unit is comprised of a resin mold body 136, female connectors 137, and lead terminals 138. Similar to the male connector unit, this female connector unit is connected by soldering using the lead terminals 138 to connecting pads 140 formed on a circuit board 139. By inserting the male connectors 132 into the female connectors 137, the circuit boards 134 and 139 can be electrically connected to each other.
In the connecting device constructed as described above, a dead space on the circuit board was large and a mounting strength to the circuit board was also not sufficient enough.
However, as the first and the second connecting devices 29 and 31 of the conventional apparatus shown in FIG. 1 are very large in size, they require soldering processes for electrical connections to magnetic heads and a rotor, the manufacturing processes are complicated. Further, a spring contact type connecting device 154, as shown in FIG. 4, were conceived by the inventors as a substitute for the first connecting device 149. However, these spring contact type connecting devices 154 are also required to penetrate the rotary drum 141, so that a space on the rotary drum 141 for providing a connecting device for connecting the circuit boards 134, 139 and the magnetic heads has been lost. Further, when it is attempted to house a circuit board 150 in the rotary drum 141, it was extremely difficult for such connecting devices as described above to electrically connect the magnetic heads and the rotary transformer to the circuit boards 134, 139.
In the conventional connecting devices used in the rotary magnetic head apparatus, its connecting method was complicated, and furthermore the connecting device itself was large in size so that it was very difficult to house a circuit board in a rotary drum, and a dead space on a circuit board was large and a mounting strength to a circuit board was also insufficient.